The concept of a cementless isoelastic monoblock cup made of highly cross-linked polyethylene infused with vitamin E: radiological analyses of migration and wear using EBRA and clinical outcomes at mid-term follow-up.

BACKGROUND

The newest generation of cementless titanium-coated, isoelastic monoblock cup with vitamin E-blended highly cross-linked polyethylene (HXLPE) was introduced to the market in 2009. The aim of the present study was to obtain mid-term follow-up data including migration and wear analyses.

METHODS

This prospective study investigated 101 primary total hip arthroplasty (THA) cases in 96 patients treated at a single institution. Patients were allowed full weight-bearing on the first day postoperatively. Harris hip score (HHS) and pain and satisfication on a visual analogue scale (VAS) were assessed at a mean follow-up of 79.0 months. Migration and wear were assessed using Einzel-Bild-Roentgen-Analyse (EBRA) software. Radiological acetabular bone alterations and complications were documented.

RESULTS

At mid-term follow-up (mean 79.0 months, range: 51.8-101.7), 81 cases with complete clinical and radiological data were analyzed. Utilisable EBRA measurements were obtained for 42 hips. The mean HHS was 91.1 (range 38.0-100.0), VAS satisfaction was 9.6 (range 6.0-10.0), VAS rest pain was 0.2 (range 0.0-4.0), and VAS load pain was 0.6 (range 0.0-9.0). Mean migration was 0.86 mm (range: 0.0-2.56) at 24 months and 1.34 mm (range: 0.09-3.14) at 5 years, and the mean annual migration rate was 0.22 (range: - 0.24-1.34). The mean total wear was 0.4 mm (range: 0.03-1.0), corresponding to a mean annual wear rate of 0.06 mm per year (range: 0.0-0.17). Radiographic analysis did not reveal any cases of osteolysis, and no revision surgeries had to be performed.

CONCLUSIONS

After using vitamin-E blended HXLPE in cementless isoelastic monoblock cups, there were no obvious signs of osteolysis or aseptic loosening occurred. No patients required revision surgery after mid-term follow-up. Cup migration and wear values were well below the benchmarks considered predictive for potential future failure.

TRIAL REGISTRATION: The trial registration number on ClinicalTrials.gov : NCT04322916 (retrospectively registered at 26.03.2020).